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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

458

(b)  The saponification number (y) due to the wax will be given by

TOO : 95 = 10-26 : y,
so that

y = 975-

This number y is deducted from the saponification number found for the sub-
stance,

847-975 = 74-95.
and from this the stearic acid (z) is deduced from the proportion,

207 : TOO = 74-95 \z,
so that,

2 = 36-11% of stearic acid.

(c)  The solid paraffin is then given by difference,

100 — (10-26 -f- 36-11) = 53-63% of paraffin.

(d)  The composition of the entire candle  (with the wick) is thus :

Wick.........0-40%

Wax .        .        .        .         .         .         .         .         .10-22

Stearic acid        ......         .     35-96

Paraffin     ........    53-42

2. Determination of the paraffin (or ceresine) alone. In this case 10 grams
oi the candle are boiled for 3-4 hours with alcoholic potash in a flask fitted
with a long tube to act as reflux condenser and then left to cool until the
paraffin has set well at the suiface of the liquid. The latter is then poured
off together with all the unsaponifiable matters of the wax which remain
suspended in a flocculent form, care being taken that the whole of the
paraffin remains in the flask. The paraffin is then again boiled for an hour
with alcoholic potash, the whole being afterwards transferred while still
hot to a separating funnel, the flask being rinsed out with boiling water
so as to obtain all the paraffin in the funnel. The aqueous alcoholic liquid
is run away and the paraffin remaining in the funnel washed several times
with hot water and subsequently rinsed out into a small beaker with the
help of very hot water. After cooling, the solid paraffin disc is dried at
100-105° in a tared dish and weighed.

This paraffin is then tested for ceresine by the methods given under
Paraffin wax and Ceresine.

2.  Illuminating Power.—This is measured as with petroleum  (see
Chapter VIII, Lighting Oil, 7).

3.  Bending Test.—This test, made especially with paraffin candles,
consists in introducing the base of the candle into a suitable support so that
the candle is horizontal and leaving it in a room at a constant temperature
of 22-25° for some hours to ascertain if it becomes curved and, if so, to
what extent.   A standard candle is used for purposes of comparison.

SOAPS

Soaps consist essentially of potassium or sodium salts of fatty acids,
potash soaps being soft and the more common soda soaps hard.

Besides these salts, all soaps contain water and, according to their
method of manufacture and use : free alkali (hydroxides or carbonates),
neutral fat, colophony (as alkali resinates), and various extraneous sub-ion         ,,    = 84-7,